Complementary metal-oxide-semiconductor (CMOS) technology is the dominant semiconductor technology used for the manufacture of ultra-large scale integrated (ULSI) circuits today. Size reduction of the semiconductor structures has provided significant improvement in the speed, performance, circuit density, and cost per unit function of semiconductor chips over the past few decades. Significant challenges, however, are faced as the sizes of CMOS devices continue to decrease.
One such challenge is soft errors. Soft errors are errors that occur in the logic state of a circuit due to excess charge carriers, which are typically induced by alpha-particles and cosmic ray neutrons. As the excess charge carriers are induced into a circuit, the logic values may be altered. For example, a logic value of a capacitor or line may be altered from a logic “0” to a logic “1,” transistor gates may be turned off or on, or the like. Soft errors occurring in SRAM devices or other memory devices can cause the stored data to become corrupted.
Attempts have been made to limit the effect of excess charge carriers and soft errors on integrated circuits. One such attempt involves the addition of error-correcting circuitry (ECC). Another attempt involves lowering the size ratio for the pull up device to pull down device sizes to below 0.75, in order to provide cell size reduction. These attempts, however, generally require additional circuitry, additional processing, and increased power requirements. Such requirements may adversely affect the design and fabrication of more robust memory circuits. Hence, a need exists for ways to reduce or eliminate soft errors in a semiconductor device and improve memory cell stability in an SRAM device.